A number of systems are in use today that employ parachutes for lowering objects and people to the ground. In the simplest systems, cargo or supplies are attached to a parachute, and simply pushed from an aircraft over an area where the supplies are needed. In more complicated such systems, the parachute may be guided, as by a GPS control system associated with the parachute, so that the parachute is directed to specific GPS coordinates. In these systems, control lines from the guidance system are pulled or released to deform a portion of the parachute, causing the parachute to change direction.
Also in the prior art are powered parachutes where a person is strapped into a harness attached to the parachute, with an engine having a propeller oriented on the person's back. The engine and propeller provide thrust, with direction and altitude controlled by the person manually operating control lines attached to the parachute.
U.S. Pat. No. 7,467,762 B1 (Parsons) teaches how to overcome weaknesses of rockets and parafoils by using weather cocking, and explains how his rocket launch system will seek a prevailing wind. He discusses overcoming this issue, along with the winds effect on the parafoil, by using the phenomenon of weather cocking to his advantage. This is by no means a new theory and has been known, if not by the same name, since man threw the first spear or shot the first arrow in a windy environment. To overcome this phenomenon, one angles the projectile, whatever it is, towards the wind knowing that the relative wind will move the projectile in the opposite direction.
Similar to Parsons initial test flights, one propulsion design of the instant invention for the original prototype had its solid-rocket motor at the rear of the rocket, as well as a set of guidance fins at the rear of the rocket. Also similar to Parson's experiments, the rocket was very unstable with the small protruding fins, so larger fins were installed to increase stability. Though stability was increased, payload weights, as well as the center of gravity and center of pressure of the thrust had to be closely monitored to prevent instability issues.
For small rocket systems, such as shoulder fired and mobile rocket systems, the disadvantage of larger fins required larger storage space within the launching tube, or the fins designed to be folded, either within a recess in the rocket itself, or against an exterior of the rocket. Such folding fins are typically spring-loaded so that they rapidly unfold and are locked in place after leaving a launch tube. Folding fins have their advantages, such as a larger design, but the disadvantages are more weight due to the folding mechanisms and larger fins, and more chances of mechanical failure during deployment. In some instances, folding fins occupy a significant amount of vertical space for storage, which increases the size of the launch vehicle and launching system.
In manned spacecraft, one or more solid fuel emergency escape rockets are mounted above a capsule containing one or more space travelers, the capsule being atop a multi-stage launch vehicle that lifts the capsule out of the Earth's gravity well. In the event of a catastrophic malfunction of the launch vehicle, the escape rocket is ignited near simultaneously with releasing the capsule from the launch vehicle, and the escape rocket quickly pulls the capsule away from the malfunctioning launch vehicle. After the escape rocket burns out, a parachute is deployed that safely lowers the capsule back to Earth. Since the escape rocket is mounted above the capsule, it should always seek an upward direction because gravity acting on the mass of the capsule pulls the capsule downward and drags the rocket and capsule into a vertical orientation. However, since this is an emergency escape rocket system, the G-forces are as extreme as a human being can stand, and no consideration is made with respect to damage to the capsule and associated components by such G-forces. Also, the parachute is unguided and unpowered, so the capsule and parachute cannot be directed to a landing zone.
In many combat and crime situations, it is desirable to have an “eye in the sky” for surveillance purposes. While hand-launched fixed and rotary wing UAVs have been developed that may be applied to this purpose, such UAVs have disadvantages. Initially, an operator must have at least some flight training. Also, in many instances, such small fixed wing UAVs require the operator to stand and throw the UAV in the manner of a glider, which may not be possible in some combat situations. Further, the UAV and associated equipment are bulky, approximately the size of a small suitcase at best, and may be difficult to carry into a combat situation. Further, it takes time to unpack the UAV from its case, assemble it as necessary and prepare it for flight. Also, such UAVs are relatively fast and cannot easily be maneuvered into cramped areas, require constant power to maintain flight and constant attention from a user in order to direct the UAV over a desired area.
In other instances, such as damaged nuclear power plants, chemical plants, train and vehicle wrecks involving hazardous materials and other similar situations, it is desirable to have a UAV equipped with a camera and video transmitter that can be flown into the hazardous area in order to access the situation. However, a small fixed wing UAV typically flies too fast to easily maneuver within a cramped area, and has a limited flight time. A rotary wing UAV can be maneuvered easily in cramped areas, but they also have limited flight times and require more power to fly slow or hover than to fly fast.
In another embodiment of the invention, a parachute or parafoil UAV is convertible to a fixed wing UAV. In this embodiment, the power and control module separates from the parafoil, and extendable wings are deployed and locked in place for fixed wing flight.
From the foregoing, it is apparent that there is a need for an inherently stable, relatively slow, small unmanned aerial vehicle system at least for reconnaissance, and which provides maneuverability of a powered fixed-wing craft and has a deployment time of a shoulder launched rocket. There is also a need for a parafoil UAV to convert to a fixed wing maneuverable vehicle for powered fixed wing flight.